Generally, metal complex formazan derivatives are used as complex salt of divalent or trivalent metal such as copper, nickel, cobalt and chromium, have brighter colors than conventional azo dyes, and have an excellent compatibility with the other color dyes as compared with anthraquinone or dioxazine-based dyes.
Formazan derivatives as reactive dyes which have a form of copper complex or have a vinylsulfone group or both of vinylsulfone group and monochlorotriazine, have been developed long time ago. The conventional formazan are mostly tricyclic. Most of them are 2-carboxyl-5-sulfo-phenylhydrazine as hydrazine compound. These tricyclic formazans are expensive in manufactruing and poor in stability for alkali at the time of room tepperature immersion (cold pad) dyeing.
Typical tricyclic formazan compounds have the following formula: ##STR1## Specifically, Japanese Patent Publication No. 81-4783 describes a compound represented by the below formula: ##STR2##
However, the said compound of Japanese Patent Publication No.81-4783 is not good in solubility, dyeing property and state of remained bath. In addition, Japanese Patent Publication Sho 55-12187 and EP 0,099,721 disclose tricyclic formazan derivatives as dye similiar to the compound of the Japanese Patent Publication No.81-4783. But, these dyes are expensive in manufacturing cost and are not good in fastness.
Further, United Kingdom Patent Publication 1,194,504 discloses dicyclic formazan derivatives having the following formula: ##STR3##
The said dicyclic formazan derivatives is also not good in fastness and dyeing property.
U.S. Pat. No. 4,607,098 discloses a compound of the following formula which has more improved fastness than the said dicyclic formazan derivatives: ##STR4## However, these formazan compounds known in U.S. Pat. No. 4,607,098 have also somewhat problems in dyeing property and chlorine water.